In sorting of articles for delivery to predetermined locations, it has been heretofore suggested to encode the memory of sortation systems to deliver the articles as required.
However, it is desirable to maximize the flow rate and sorting rate by minimizing the spacing between successive articles even though the articles vary in length.
Other prior control devices have no means for measuring the length of objects while controlling the object spacing in a manner to permit maximum flow and sort rate. They consumed extra but unnecessary distance to measure object length, thus forcing inefficient flow rates. They have not controlled release of succeeding articles on the basis of measured length of the articles.
Accordingly an object of this invention is to perform these measurements and control functions to achieve maximum system efficiency by finding the center or other position of objects such as boxes, mail sacks, luggage, cartons, and other goods conveyed on sorting systems, and controlling the rate at which they are inducted or entered onto the conveyor device.
A further object of the invention is to provide a method and apparatus for delivering articles to predetermined locations at a rate which is determined by the velocity of the conveyor, the length of time that a diverter interferes with the free flow of objects, the effective length of the diverters, the length of the objects, and the spacing between them.
Previous devices also prevented the entry of address information until the goods passed a point where their length was measured by means of a photosensing device. This delay inhibited the rate of flow of goods. A further object of this invention is to provide greater flexibility for entry of address information into the sort system control device by a design which does not inhibit the rate of flow but provides a sufficient span of time which will permit entry of the address information prior to passage at the measuring position, without loss of control.
Another object of the invention is to provide a means of ignoring false indication of goods which may occur when the sensing device is interrupted by irregular outlines, reflective surfaces, and appendages to the object, such as tags and handles.
Other prior systems use techniques which prevent the control device from remembering information if the conveyor stops, and which depend upon a time period measurement increment fixed by a predetermined constant, such as a 60-cycle AC line frequency. Accordingly a further object is to provide a means of measurement and control for conveyor motion at different velocities, and if the conveyor momentarily stops forward motion by using a timing pulse which is derived from the conveyor moving surface, regardless of the velocity, and which device is designed to retain memory of received information if the conveyor stops and to hold it until the system resumes operation.
Other prior devices depend upon the entry of address information by human operators, and therefore are inhibited by the alertness and desire of the operator. Another object of the invention is to provide a means for both manual and automatic entry of address information into the control device which uses induction of material onto a sortation conveyor by computed object spacing without inhibition by entry of address information; and which also permits automatic address reading while maintaining maximum flow of goods.